The Mangatainoka River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 that flows in the Wairarapa

Wairarapa

Wairarapa is a geographical region of New Zealand. It occupies the south-eastern corner of the North Island, east of metropolitan Wellington and south-west of the Hawke's Bay region. It is lightly populated, having several rural service towns, with Masterton being the largest...

 region of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

's North Island

North Island

The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

. Its headwaters are on the eastern side of the Tararua Range

Tararua Range

The Tararua Range is one of several mountain ranges in the North Island of New Zealand which form a ridge running parallel with the east coast of the island between East Cape and Wellington....

 to the southwest of the town of Eketahuna

Eketahuna

Eketahuna is a small rural service town, the most southerly in the Tararua District in the Manawatu-Wanganui region of the North Island of New Zealand, but is considered to be in northern Wairarapa. It was called Mellenskov, but was renamed soon after its founding.The town is located at the foot of...

, and it roughly parallels the Wairarapa Line

Wairarapa Line

The Wairarapa Line is a secondary railway line in the south-east of the North Island of New Zealand, connecting the capital city of Wellington with the Wairarapa region. The line ends at Woodville, where it joins the Palmerston North - Gisborne Line...

 railway and State Highway 2

New Zealand State Highway network

The New Zealand State Highway network is the major national highway network in New Zealand. Just under 100 roads in both the North and South Islands are State Highways...

 through the northern Wairarapa before meeting the Tiraumea River

Tiraumea River

Tiraumea River is the name of two rivers in New Zealand.* Tiraumea River * Tiraumea River...

 just before its confluence

Confluence (geography)

In geography, a confluence is the meeting of two or more bodies of water. It usually refers to the point where two streams flow together, merging into a single stream...

 with the Manawatu River

Manawatu River

The Manawatu River is a major river of the southern North Island of New Zealand.The river has its headwaters to the northwest of Norsewood in the Ruahine Ranges of southern Hawke's Bay. It flows initially eastward before turning south-west near Ormondville, flowing 40 km before turning...

 just south of Woodville

Woodville, New Zealand

Woodville is a small town in the southern North Island of New Zealand, 75 km north of Masterton and 25 km east of Palmerston North. In the 2006 census 1,398 people are usually resident in Woodville, a decrease of 81 people, or 5.5%, since the 2001 Census.-Early History and Local...

. The railway's 162 metre bridge across the river between Newman and Hukanui is the longest on the entire line. and further to the north, the small settlement of Mangatainoka

Mangatainoka

Mangatainoka is a small settlement in northern Wairarapa Bush, New Zealand. It is located between Pahiatua to the south and Woodville to the north and is intersected by the Mangatainoka River. The 2001 New Zealand Census of Population and Dwellings gave its population as 1,617, consisting of 858...

 sits on the river's banks north of Pahiatua

Pahiatua

Pahiatua is a rural service town in the south-eastern North Island of New Zealand with an urban and rural population of over 4,000. It is between Masterton and Woodville on State Highway 2 and the Wairarapa Line railway, north of Masterton and east of Palmerston North...

.

Prior to European settlement of New Zealand, the shallow river was thickly lined with matai

Prumnopitys taxifolia

Prumnopitys taxifolia is an endemic New Zealand coniferous tree that grows on the North Island and South Island. It also occurs on Stewart Island/Rakiura but is uncommon there....

, rimu

Dacrydium cupressinum

Dacrydium cupressinum, commonly known as rimu, is a large evergreen coniferous tree endemic to the forests of New Zealand. It is a member of the southern conifer group, the podocarps. The former name "red pine" has fallen out of common use....

, and totara

Podocarpus totara

Podocarpus totara is a species of podocarp tree endemic to New Zealand. It grows throughout the North Island and northeastern South Island in lowland, montane and lower subalpine forest at elevations of up to 600 m.-Description:...

 trees that prevented serious flooding to the swampy lands alongside the river. However, large-scale removal of the forest and drainage of the fertile land for agriculture

Agriculture

Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 has caused the river to flow faster, deepening its channel

Channel (geography)

In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks.A channel is also the natural or human-made deeper course through a reef, sand bar, bay, or any shallow body of water...

, heightening erosion

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

, and encouraging it to meander to try to return to its slower pace. This has resulted in devastating floods, including one in October 2000 that caused at least NZ$

New Zealand dollar

The New Zealand dollar is the currency of New Zealand. It also circulates in the Cook Islands , Niue, Tokelau, and the Pitcairn Islands. It is divided into 100 cents....

200,000-300,000 of damage to the regional council's scheme to stabilise the river and rehabilitate its environment.

The river is popular for fishing

Fishing

Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

, especially for trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

. Approximately 50 km of the river is fishable, and due to its proximity to State Highway 2 and major northern Wairarapa towns, access is easy.